1. The Most Conceptually Complicated Trait

Of all the Big Five personality traits, agreeableness is perhaps the most misunderstood — and, according to Peterson (2017), the most conceptually complicated. This is partly a naming problem: compassion and politeness sound unambiguously positive, as do the adjectives that describe the agreeable person: warm, kind, cooperative, forgiving, and sympathetic. The adjectives that describe the disagreeable person — irritable, ruthless, rude, vengeful, callous — sound unambiguously negative.

But here is the problem with that framing: personality traits are normally distributed. That means there are genuine advantages and disadvantages at every position on the distribution — including the positions that sound negative. If low agreeableness were purely a liability, natural selection would have eliminated it long ago. It has not. The disagreeable end of the distribution has persisted because it confers real advantages — in competitive environments, in negotiations, in leadership, in earnings, and in the capacity to maintain one’s own interests without resentment. The task of this article is to take both poles seriously.

2. What Is Agreeableness?

Agreeableness is the Big Five personality trait that describes the fundamental social problem of how much to weigh others’ interests against your own [Peterson, 2017]. Agreeable individuals are courteous, friendly, tolerant, cooperative, considerate, modest, trustworthy, helpful, altruistic, and empathetic [Costa and McCrae, 1992]. They are good-natured, warm-hearted, forgiving, and sympathetic. They care about others — genuinely, not instrumentally — and they invest in maintaining positive relationships even at personal cost. Disagreeable individuals are, at the low end, direct, competitive, sceptical, hard-headed, and, at the extreme, ruthless, callous, and vengeful [Peterson, 2017].

The evolutionary framing is useful here. Agreeable people evolved, in a meaningful sense, for the care of those who are dependent and vulnerable — infants, the sick, the elderly. Compassion as a negotiating stance means systematically negotiating on behalf of the other person rather than your own [Peterson, 2017]. This is the right strategy when the other party has to be right — as infants do, as sick people do — but it becomes a liability when deployed indiscriminately in competitive professional contexts where the other party will simply take what they are given. Disagreeable individuals, by contrast, evolved for predatory behaviour in the competitive sense: they are adapted to pursue their own interests effectively in competitive, zero-sum contexts [Peterson, 2017].

2.1 Two Distinct Aspects: Compassion and Politeness

Agreeableness divides into two separable aspects with different profiles [Peterson, 2017]:

Compassion is the empathy-driven, care-oriented dimension. Compassionate individuals feel others’ emotions, inquire about others’ well-being, sympathise with others’ feelings, take time for others, and like to do things for others. Peterson (2017) frames compassion as fundamentally a negotiating stance: the more compassionate you are, the more you negotiate on the other person’s behalf rather than your own — appropriate when dealing with genuine dependency (infants, the vulnerable), potentially counterproductive when deployed against competitive counterparts who are negotiating on their own behalf.